Settings > Device Preferences > About > System Update.
Many technicians upload firmware links in the descriptions of repair videos. For instance, channels like Onida Stock Firmware provide links for various Onida Android device updates. How to Update via USB Download ONIDA LEO43FIAB2 Software part01 rar
Installing incorrect firmware can permanently "brick" your TV. Always verify that the firmware matches your TV's Main Board Number (e.g., TP.MT5507.PB801) before flashing. Settings > Device Preferences > About > System Update